>When I read this question, I thought of one of the Dr. Seuss books,
>_Marvin K. Mooney, Will You Please Go Now?_, and this couplet,
> "Please, Marvin K.,
> Be on your way!"
>
>"Be on your way," I believe, translates the present imptv POREUOU very
>accurately.

Nicely put!

As I see it, the emphasis is not on arriving in Egypt, but on fleeing,
getting away from the present danger, getting into motion. If the intent
were to say, "Get yourself to Egypt", an Aorist would have been used.